How to restrict admin login during RDP maintenance?

Question

Windows

Gentlemen, I remember there was an opportunity, but I don’t remember how it was done, to limit the entrance of administrators to the RDP.
Let's say the server is being serviced, or there was an accident, and you need to make sure that the admins do not kick each other out.
If there are no logged-in two admins on the server, then you can enter, but if "all places are occupied" - then you cannot enter through the RDP. Those. You can't kick out those who are logged in. Roughly speaking, you need to disable the request about which user needs to be knocked out in order to enter.
Tell me how is this done?

Answer 1

Do not issue one login to different people and resolve (disable access) at the user level when you need. These users may not even have administrator access, but immediately after login, you can cascade the session already under the administrator.
Those. user_1 logs in, in the scheduler there is a script to disable user_2 when logging in, and turning it on when logging out, after logging in, a session immediately opens to the Administrator user (or a console that only one user can use at a time), if you set the rights, switching the console is possible directly in the task manager (tab - users, right button - expand).

Answer 2

I once closed access via RDP through the local group policy. Details are described here